The invention relates to a tape recorder employing a miniature tape cassette and capable of automatic reversible operation, and more particularly, to such a tape recorder which enables both a record and playback operation in either direction of running of a tape contained in a miniature tape cassette.
As is well recognized, a stereophonic tape recorder is known employing a tape cassette of a size, commonly referred to as a compact cassette, and capable of automatic reversible operation. Such a tape recorder utilizes a 4-track 4-channel magnetic head assembly 1 as shown in FIG. 1. The assembly 1 includes four magnetic heads, not shown, which are received within a shield casing 2, and the casing 2 is formed with a front curved wall in which four transversely elongate, rectangular windows 3a-3d are formed in vertical alignment with each other and through which the record/playback gaps 4a-4d of the four magnetic heads are exposed. It should be understood that the gaps 4a-4d are located in alignment with a magnetic tape 5 (see FIG. 5) which is contained in the compact cassette. During the running of the tape 5 in a forward direction, the upper two of the magnetic heads are activated to enable left- and right-hand channel signals to be recorded on or reproduced from a first and a second track 6a, 6b of the tape 5. Conversely, when the tape 5 runs in a reverse direction, the lower two of the magnetic heads are activated to enable left- and right-hand channel signals to be recorded on or reproduced from a third and a fourth track 6c, 6d of the tape 5.
In a compact cassette, the upper and lower walls in the region of a window which receive the magnetic head assembly 1 projects vertically beyond the outer wall of the remainder of the cassette, whereby the window has an increased area. Accordingly, it is a rather simple matter to manufacture a magnetic head assembly such as shown at 1 which can be inserted into the window. However, when a miniature tape cassette, which is commonly referred to as micro-cassette (registered trademark), the size of the cassette itself is reduced to one-quarter that of the compact cassette, and in addition, as shown in FIG. 4, windows 21, 22 each of which receives an associated magnetic head have upper and lower walls which do not project beyond the outer wall of the cassette 11, whereby the windows 21, 22 are narrow ones. Hence, it will be seen that it will be very difficult to manufacture a multiple channel magnetic head assembly which is capable of enabling a stereophonic record/playback operation by itself in a tape recorder employing such miniature tape cassette 11. If the manufacture is possible, the yield of manufacture will disadvantageously be very low.
On the other hand, it is also recognized that in currently used tape recorders capable of automatic reversible operation, there is an inconvenience that the tape running condition is not always the same during its running in both the forward and the reverse direction. This is attributable to a poor parallelism between a capstan and a pinch roller or a skewed mounting of guide pins and guide rollers within the cassette.
By way of example, FIG. 3 illustrates a record/playback operation utilizing a multiple channel head assembly 1. It may be assumed that when the tape 5 runs in the forward direction or in a direction indicated by an arrow a, there is no misalignment in azimuth with respect to the head 1, as illustrated at 5A, to permit an accurate record/playback operation. However, when the tape runs in the reverse direction or in a direction indicated by an arrow b, a misalignment in azimuth may occur as indicated at 5B, to prevent an accurate record/playback operation from being achieved. Thus the input or output to or from the tape 5 may change depending on the direction of running of the tape 5, causing a degraded frequency response during the time tape runs in the reverse direction.